When a laser with 543, 668 or 790 +/- 50 nm was used to irradiate the reduced polyaniline film on an indium tin oxide electrode in hydrochloric acid, the light was scattered in all directions. The intensity of the scattered light decreased with increase in the detection angle up to the right angle. When the electrode potential was scanned between the insulating and the conducting domain, the intensity varied sigmoidally with hysteresis. The intensity increased with a decrease in the absorbance. The scattering of the light can be ascribed to multiple reflection, luminescence, or Rayleigh scattering. The spectra of the scattered light was identical with that of the incident light, suggesting the absence of luminescence. The intensity increased with an increase in thickness of the film, indicating a negligible contribution of multiple reflection. Since the volume of the oxidized film is larger than that of the reduced one, the film synthesized in the oxidized state is deformed by the electrode reduction. Then, the film density becomes locally inhomogeneous and this may give rise to the Rayleigh scattering. The potential-variation of the light scattering occurred at a more negative potential than that of the absorbance at 310 nm and of the current did.